I think Tybalt is the blame. He is the one who started the sword fight. He is the one that killed Mercutio. He is the one that got Romeo banished. Now Romeo can't see Juliet. He knew the bad things that would happen to Romeo and Juliet if they did every get married. Romeo would get banished or die. Juliet would get disowned my her family. He was the one that at the party heard what Romeo said and almost started a fight at the party.